HLA-Dr-unrestricted accessory cell function in human neutrophils

Human polymorphonuclear leukocytes (PMN) were purified from purified protein derivative (PPD)-immune individuals and assayed for their ability to act as antigen-presenting cells for PPD to autologous purified lymphocytes or as accessory cells in a PHA mitogenic response with autologous lymphocytes. PMNs were very efficient accessory cells in that the PHA mitogenic response was augmented fourfold by the addition of PMNs to the culture. In contrast, PMNs did not appear to present antigen. Accessory cell function by PMNs was HLA unrestricted in that allogeneic PMNs were equally effective accessory cells. Furthermore, the accessory cell function of PMNs appeared to require cell-cell contact, since culture supernatants from PMNs failed to replace intact PMNs in the mitogenic response.